16:26 a great earthquake. This was a notable miracle of providence, as distinct from creation miracles such as Paul’s restoration to life after stoning. There is nothing supernatural about earthquakes. However, the rate of occurrence of earthquakes in Philippian jails where Christian missionaries who had been unjustly imprisoned and beaten, yet were singing and praying and praising God at midnight, is very low! God—and no doubt His angels as well—can surely control the rate, timing and location of the processes of nature which He created.

16:30 what must I do. In such a city as Philippi, so thoroughly committed to pantheistic occultism and so antipathetic to Jewish monotheism, it would take a notable testimonial miracle to provide a breakthrough for the gospel among its Greek citizenry. The jailer immediately recognized that such a miracle had occurred, and that these men were, indeed, as the evil spirit in the damsel had proclaimed, “servants of the Most High God,” who could show him “the way of salvation.” Hence his question.

16:31 and thy house. It is noteworthy that Paul promised the salvation, not of the jailer only, but also all his “house,” if he would believe on Christ. Similarly God long ago told Noah: “Come thou and all thy house into the ark; for thee have I seen righteous before me in this generation” (Genesis 7:1). Paul proceeded to speak to the jailer “the word of the Lord, and to all that were in his house” (Acts 16:32), and they all believed and were baptized. Even though each had to believe individually, they did believe, just as Paul had promised. In some way we cannot comprehend, God works in such a way that, when a father believes and faithfully obeys the Lord, sooner or later, his children will come as well.

16:38 they were Romans. Paul’s father in Tarsus evidently had been awarded Roman citizenship for services to the state, so Paul (and presumably Silas) had been born with such citizenship. This involved many privileges and protections established in Roman law.